Andrew Alek Tuen

Varied Response of Western Pacific Hydrology to Climate Forcings over the Last Glacial Period

Borneo Paleohydrology Climate records of the last glacial cycle provide a good picture of how climate changed at high and middle latitudes, but fewer records of the tropics are available. Carolin et al. (p. 1564, published online 6 June) present data from a suite of precisely dated stalagmites from Borneo that reveal how the western tropical Pacific region behaved between 100,000 and 15,000 years ago, a period during which many abrupt climate changes occurred in other parts of the world. While the hydroclimate of Borneo changed in response to precessional forcing, it responded only weakly to the forces that produced glacial-interglacial changes in global climate. Stalagmites from Borneo show how the climate of the western equatorial Pacific region changed over the past 100,000 years. Atmospheric deep convection in the west Pacific plays a key role in the global heat and moisture budgets, yet its response to orbital and abrupt climate change events is poorly resolved. Here, we present four absolutely dated, overlapping stalagmite oxygen isotopic records from northern Borneo that span most of the last glacial cycle. The records suggest that northern Borneo’s hydroclimate shifted in phase with precessional forcing but was only weakly affected by glacial-interglacial changes in global climate boundary conditions. Regional convection likely decreased during Heinrich events, but other Northern Hemisphere abrupt climate change events are notably absent. The new records suggest that the deep tropical Pacific hydroclimate variability may have played an important role in shaping the global response to the largest abrupt climate change events.

Tree shrew lavatories: a novel nitrogen sequestration strategy in a tropical pitcher plant

Nepenthes pitcher plants are typically carnivorous, producing pitchers with varying combinations of epicuticular wax crystals, viscoelastic fluids and slippery peristomes to trap arthropod prey, especially ants. However, ant densities are low in tropical montane habitats, thereby limiting the potential benefits of the carnivorous syndrome. Nepenthes lowii, a montane species from Borneo, produces two types of pitchers that differ greatly in form and function. Pitchers produced by immature plants conform to the ‘typical’ Nepenthes pattern, catching arthropod prey. However, pitchers produced by mature N. lowii plants lack the features associated with carnivory and are instead visited by tree shrews, which defaecate into them after feeding on exudates that accumulate on the pitcher lid. We tested the hypothesis that tree shrew faeces represent a significant nitrogen (N) source for N. lowii, finding that it accounts for between 57 and 100 per cent of foliar N in mature N. lowii plants. Thus, N. lowii employs a diversified N sequestration strategy, gaining access to a N source that is not available to sympatric congeners. The interaction between N. lowii and tree shrews appears to be a mutualism based on the exchange of food sources that are scarce in their montane habitat.

Transformation of ENSO‐related rainwater to dripwater δ18O variability by vadose water mixing

Speleothem oxygen isotopes (δ18O) are often used to reconstruct past rainfall δ18O variability, and thereby hydroclimate changes, in many regions of the world. However, poor constraints on the karst hydrological processes that transform rainfall signals into cave dripwater add significant uncertainty to interpretations of speleothem-based reconstructions. Here we present several 6.5 year, biweekly dripwater δ18O time series from northern Borneo and compare them to local rainfall δ18O variability. We demonstrate that vadose water mixing is the primary rainfall-to-dripwater transformation process at our site, where dripwater δ18O reflects amount-weighted rainfall δ18O integrated over the previous 3–10 months. We document large interannual dripwater δ18O variability related to the El Nino–Southern Oscillation (ENSO), with amplitudes inversely correlated to dripwater residence times. According to a simple stalagmite forward model, asymmetrical ENSO extremes produce significant offsets in stalagmite δ18O time series given different dripwater residence times. Our study highlights the utility of generating multiyear, paired time series of rainfall and dripwater δ18O to aid interpretations of stalagmite δ18O reconstructions.

Wild and valuable? Tourist values for orang-utan conservation in Sarawak

Fluffy, orange and endearing, orang-utans have won the hearts of people all over the world. However, all sub-species are endangered in the wild with the Bornean orang-utan population having declined by more than 50% over the past 60 years. Fewer than 2,000 wild orang-utans remain in Sarawak with nearly all truly wild ones confined to a remote site on the Indonesian border. Yet each year thousands of tourists and local Sarawak people see orang-utans semi-wild in a reserve or captive in a rehabilitation centre. We investigated the attitudes of such tourists towards the conservation of the remaining wild populations by means of questionnaires, including a choice experiment. Sixty percent of the respondents were, in principle, willing to pay to ensure survival of a wild orang-utan population. International tourists tended to regard wild survival as being more important than having a high probability of seeing orang-utans personally-indeed they preferred wild orang-utans to be hard to find. Malaysian tourists were more inclined to favour investment in the small number of captive or semi-wild animals. Using conservative judgements of the difference between stated and real willingness-to-pay, we estimated that about USD 6.6 million per year could be made available to wild orang-utan conservation from voluntary contributions by visitors to the semi-wild animals. We also estimated that the 40% of visitors to these facilities who come to Sarawak primarily because of the apes, bring between USD 13 and USD 23 million into the local economy each year through their expenditure on local businesses, about 0.6% of the income earned by Sarawak from timber products. Our results suggest that far fewer would come if there were no wild orang-utans in Sarawak. Thus the value of wild orang-utans in Sarawak can be delivered through the captive facilities but the economic benefits from orang-utans require both captive and wild orang-utans.

Occurrence of a mosquito vector in bird houses: Developmental consequences and potential epidemiological implications

Even with continuous vector control, dengue is still a growing threat to public health in Southeast Asia. Main causes comprise difficulties in identifying productive breeding sites and inappropriate targeted chemical interventions. In this region, rural families keep live birds in backyards and dengue mosquitoes have been reported in containers in the cages. To focus on this particular breeding site, we examined the capacity of bird fecal matter (BFM) from the spotted dove, to support Aedes albopictus larval growth. The impact of BFM larval uptake on some adult fitness traits influencing vectorial capacity was also investigated. In serial bioassays involving a high and low larval density (HD and LD), BFM and larval standard food (LSF) affected differently larval development. At HD, development was longer in the BFM environment. There were no appreciable mortality differences between the two treatments, which resulted in similar pupation and adult emergence successes. BFM treatment produced a better gender balance. There were comparable levels of blood uptake and egg production in BFM and LSF females at LD; that was not the case for the HD one, which resulted in bigger adults. BFM and LSF females displayed equivalent lifespans; in males, this parameter was shorter in those derived from the BFM/LD treatment. Taken together these results suggest that bird defecations successfully support the development of Ae. albopictus. Due to their cryptic aspects, containers used to supply water to encaged birds may not have been targeted by chemical interventions.

Identifying Habitat Characteristics and Critical Areas for Irrawaddy Dolphin, Orcaella brevirostris: Implications for Conservation

Irrawaddy dolphins, Orcaella brevirostris, in the Kuching Bay, Sarawak, Malaysia have been subjected to pressure from cetacean-fisheries interactions, dolphin watching tourism and coastal development. However, very little information is known about their ecology and factors driving their habitat preferences. To obtain critical information on the distribution, habitat preference and range pattern of Irrawaddy dolphins in Kuching Bay, Sarawak, systematic boat-based surveys were conducted between June 2008 and October 2012. The results showed a statistically significant relationship between Irrawaddy dolphins’ distribution and different categories of salinity, tide levels and distance to river mouths. Kruskal-Wallis tests confirmed that the presence of Irrawaddy dolphins in Kuching Bay had statistically significant relationships to habitat parameters of salinity (chi-square = 4.694, p = 0.03). Fisher’s exact test indicated that Irrawaddy dolphins were statistically more likely to be present in waters within a 6 km radius of river mouths. The distribution of dolphins was also affected by tide levels as Mann-Whitney U-tests proved a statistically significant difference in dolphin distribution between tide levels lower than 2.0 m and tide levels higher than 2.0 m (p = 3.153 × 10−11). The representative range and core area of photo-identified Irrawaddy dolphins estimated using fixed kernel range was 246.42 km2 and 37.22 km2, respectively, with core area located in the Salak Estuary. The results obtained in this study reflect dry season distribution only, and may differ during the wet season. Nonetheless, these results highlight the importance of shallow coastal waters and the overlap of Irrawaddy dolphin critical habitat with that of human activities in Kuching Bay. Conservation efforts are required to minimise the effects of the pressures exerted on these animals and their habitats.

Searching for the Haplorrhine Heterotherm : Field and Laboratory Data of Free-Ranging Tarsiers

The observation of heterothermy in a single suborder (Strepsirrhini) only within the primates is puzzling. Given that the placental-mammal ancestor was likely a heterotherm, we explored the potential for heterothermy in a primate closely related to the Strepsirrhini. Based upon phylogeny, body size and habitat stability since the Late Eocene, we selected western tarsiers (Cephalopachus bancanus) from the island of Borneo. Being the sister clade to Strepsirrhini and basal in Haplorrhini (monkeys and apes), we hypothesized that C. bancanus might have retained the heterothermic capacity observed in several small strepsirrhines. We measured resting metabolic rate, subcutaneous temperature, evaporative water loss and the percentage of heat dissipated through evaporation, at ambient temperatures between 22 and 35°C in fresh-caught wild animals (126.1 ± 2.4 g). We also measured core body temperatures in free-ranging animals. The thermoneutral zone was 25–30°C and the basal metabolic rate was 3.52 ± 0.06 W.kg−1 (0.65 ± 0.01 ml O2.g−1.h−1). There was no evidence of adaptive heterothermy in either the laboratory data or the free-ranging data. Instead, animals appeared to be cold sensitive (Tb ~ 31°C) at the lowest temperatures. We discuss possible reasons for the apparent lack of heterothermy in tarsiers, and identify putative heterotherms within Platyrrhini. We also document our concern for the vulnerability of C. bancanus to future temperature increases associated with global warming.

Applying Bipartite Network Approach to Scarce Data: Modeling Habitat Suitability of A Marine Mammal Species

Current study intends to formulate a habitat suitability model of a newly surveyed marine mammal species where the research scenario is characterized by real-world data that is scarce with no detail demographic value available. It is extremely challenging to solve it using either traditional statistical approaches where huge amount of data are required or deterministic approaches that commonly employ partial differential equations (PDE) model which are based strongly on well-established physical laws and entail detail species-specific demographic values. Conversely, the graph-theoretic based bipartite network modeling (BNM) approach is not bound by the above limitations and is thus employed in this study. The result produced is a bipartite habitat suitability network model consisting thirteen location nodes and thirteen species nodes, each with their respective parameters of which some are quantified through a machine learning algorithm, and thirty-eight weighted edges that are quantified through multiplication rule. Habitat suitability index, generated through implementation of an adapted web-based search algorithm, is produced and utilized for the ranking of these location nodes. The ranking result obtained is in good agreement with the past literature. The results produced also provide pertinent input to the related practitioners for the conservation of the species and preservation of the habitat and environment ecology.

Bird Diets in Urban Environments: The Case of the Asian Glossy Starling, Aplonis panayensis

The Asian Glossy Starling, Aplonis panayensis, is one of the most abundant birds in Kuching City, occupying nooks and cavities of buildings and soiling the walls and fl oors with their droppings. To determine why they are so abundant, we focused on their dietary habits in a study conducted in Dewan Suarah area of Kuching in 2013. A total of 51 fecal samples were collected from the fl oor of Dewan Suarah and examined for dietary fragments. The results showed the diet comprises insects as well as plant parts. The insects are solely from the Order Hymenoptera (70 individuals), whereas the plant parts comprised fi gs (86 %), Vitex sp. (2 %) and unidentifi ed plant materials (12 %). The Hymenopteran identifi ed in fecal samples belong to the family Agaonidae (45 individuals), Formicidae (18 individuals), and Ormyridae (7 individuals). There is a signifi cant difference in frequency occurrence of insects and fruits in the diet of starlings. From the fecal analysis, the insects in the diet of the starlings are mainly from the fi gs they have eaten. The diet of the bird is discussed in relation to the availability of food items in the surrounding areas.

Four Simple Questions: Evaluating the Effectiveness of Half-Day Community Workshops Designed to Increase Awareness of Coastal Cetacean Conservation Issues in Sarawak, Malaysia.

Community workshops were held in coastal locations in Sarawak to raise awareness of cetacean conservation. Interviews were conducted up to 2 years later in four “workshop communities” as well as four villages where workshops were not conducted. Comparison of responses between respondents who had attended workshops (n = 127) versus those who had not (n = 233) indicate that workshop attendence led to significantly higher rates of “correct” responses on all three basic measures of cetacean conservation awareness. However, fishermen demonstrated a low level of knowledge of how to handle accidental entanglements, indicating a need for more effective communication strategies for this target group.